Spica TC-50 Driver Replacement / Repairs

Replacement Drivers

The original drivers were manufactured by Audax (FR) / Polydax (US). Audax no longer manufactures replacement woofers. If you could find Spica graded new old stock (NOS) with the proper service codes that would be ideal, perhaps just as good would be to cannibalize a used set. Note: be sure to read about TC-50 Early / Late Model Differences below.

Other options would include non-graded (see service codes), NOS Audax (FR) / Polydax (US) replacement, which turn up on eBay from time to time, or getting your driver rewound by a rebuilder. If you go the rebuilder route, there a strong case to have your drivers redone in pairs.

For the TC-50, Madisound offers the Audax 4 ohm TW025A2 driver (specs) as a replacement tweeter. On inspection (based on the length of the voice coil), these appear to be a match for the earlier the HD 100 D25 tweeters. You should note that the terminals on the TW025A2 tweeters are located about 20 or 30 degrees apart (if the speaker were the face of a clock the terminals would be at 5 and 7 o'clock). The terminals on the original units are located 180 degrees apart (using the clock again, the terminals were at 3 and 9 o'clock), so some cabinet modification will be necessary. As these are not an exact replacement I recommend you replace them in pairs rather than mix this driver with earlier models.

Rebuilding \ Repairing Speaker Drivers

The voice coil of woofers and tweeters can be rewound by a competent speaker rebuilder. However, if you have a physically damaged cone or rubber surround (Cats!) you may be out of luck. Everyone I have contacted so far says the butyl surrounds for the woofers are no where to be found. This means a rebuilder will use foam surrounds. Foam surrounds will significantly alter the mass of the woofer and its sound.

Speaker Cone Doping

The woofers of the TC-50 and 50i were doped in a mix of Elmer's glue and water. According to the (SLUG Post 836), the Elmer's glue is mixed 60:40 glue to water (3:2). They first placed an 1/8" bead is put around the base of the cone and let it dry, then cone is coated. It is believed that the TC-50s had one coat, while TC-50i's had two coats (SLUG post 160).

TC-50 Early / Late Model Differences

In 1988 Spica offered a "revision" to existing owners and all new units after this date (post 7500 serial numbers) were built to this revised spec. I have seen these newer units referred to informally as TC-50i (improved) and TC-50II (second edition). Note that Tweeters, woofers, and crossovers changed with this revision.

Can you tell from the outside which model you have?

Early units have a rectangular hole (TC-50) in the felt surrounding the tweeter, later units have a small square hole (TC-50i). When in doubt check the actual driver manufacturer’s part numbers stamped on the drivers.

If you are replacing only one woofer, you can do this reliably by matching the service code and part number on the driver. If you are unable to locate matching service codes you can replace the drivers from a set off eBay, as long as you swap the the woofers and crossovers to maintain matching. If you are swapping late for early or vise versa, just remember that the woofers, tweeters, and crossovers were changed with the revision.

*The HIF 17JS 2 CA12Except for the SC-30 and TC-60 all Spica original drivers were manufactured by Audax of France and labeled Polydax in the US. Audax no longer manufactures replacement woofers. spec is correct for response curves etc. however,4 ohm version of this driver was used in the TC-50 and the 8 ohm verion in the SC-50.